1. Technical Field
The present invention relates to a projector, and a projection condition adjustment method performed using a projector.
2. Related Art
In the past, there has been known a projector, which modulates the light beam emitted from a light source to thereby form an image, and project the image on a projection target plane such as a screen in an enlarged manner. When projecting the image using such a projector, the image projected on the projection target plane might be distorted in some cases depending on the positional relationship between the projection target plane and the projector. To cope with such a problem, there has been known a projector, which calculates the relative angle and distance with respect to the projection target plane to thereby perform the correction of the keystone distortion (the keystone correction) of the image (see, e.g., JP-A-2006-60447 (Patent Document 1)).
In the projector described in Patent Document 1 described above, a grid-like pattern image having white areas and black areas alternately arranged in a 3×3 matrix is displayed, and then the pattern image is shot by an imaging section. Then, the boundary (particularly the boundary at the central portion) between the white areas and the black areas is detected from the shot image, then the position of the projection area of the image is calculated, and then the keystone distortion of the image is corrected based thereon. It should be noted that in the present projector, the focus adjustment of the projection image is also performed in accordance with the position of the projection area thus calculated.
Here, the keystone correction and the focus adjustment by the projector is performed after the projector is started up and then changed to the state in which the image projection is possible. Therefore, there arises a problem that when switching the state from display of the input image input to the projector to the display of the pattern image described above, rapid change in brightness is caused in the projection area, and therefore, imaging by the imaging section is not stabilized. Therefore, there arises a problem that it takes long time until the imaging by the imaging section is stabilized.
In contrast, it is possible to generate a calibration image obtained by superimposing the pattern image described above on an input image and then display the calibration image, and then detect the position of the projection image based on the shot image obtained by shooting the calibration image.
However, in such a case, there arises the possibility that the detection of the pattern becomes difficult under the influence of the grayscale on the periphery of the pattern depending on the input image, and the appropriate adjustment of the projection condition is hindered.